YEAST-LIKE FUNGI OF HUMAN INTESTINAL TRACT 



27 



TABLE 5 Continued 

 REACTION OF YEASTS ON SUGAR MEDIUMS 

 At 35 C. 



At 25 C. 



In sucrose and glucose at 35 C. the reactions of these are not different 

 from those of Cultures 170 and 215.13. If the cultures are allowed to 

 grow a month, however, the results are different. 



Dextrin yeast water appears to be an unusually good medium for 

 differentiating between those species which decrease acidity and those 

 which produce little change. The differences are very sharp and take 

 place within a short time, especially when the cultures are kept at 35 C. . 



On the whole, the exact determination of changes in acidity during 

 a period of growth is believed to be of little value on account of the 

 wide variation within a single species even under apparently the same 

 cultural conditions. Increase or decrease in acidity, as revealed by 

 titrations after a week or more of growth, is of value in differentiating 

 species, in that some species tend to constantly decrease the acidity 

 while others bring about no decided change. The initial acidity of 

 the mediums should be determined and stated since this has an impor- 

 tant influence on the final reaction. The substances employed in the 

 preparation of the carbohydrate mediums shoulcl be stated in all cases 

 since the carbohydrates themselves are not usually the cause of the 

 change in acidity although they may influence the reaction. 



